Press tool

ABSTRACT

Disclosed is a press tool for pressing tubular inner and outer nested workpieces (e.g. a pipe end upon which is slid a press fitting). The press tool includes a plurality of clamping components which contain clamping jaws having a continuous circumferential pressing groove (63) shaped in their inner sides, the jaws having a pressing land (65) that extends along only one side of the pressing groove. The press tool also includes a template (44) which fits over the inner nested workpiece but not over the outer slid-on workpiece, the template (44) being positioned on the side of the groove (63) opposite the pressing land (65).

The invention involves a press tool for pressing tubular, nestedworkpieces, in particular a pipe end upon which is slid a press fitting,having several clamping components which bear clamping jaws with acontinuous circumferential pressing groove shaped in their inner side,and containing a pressing land extending along only one side.

One known-in-the-art process for joining the ends of tubular workpiecesinvolves using tubular press fittings that are ductile and are comprisedof metal, preferably of steel. Such pipe joints and the associated pressfittings can be found, for example, in DE-C-1 187 870 and DE-C-40 12504.

A wide variety of designs has been developed for press tools that areintended for pressing a press fitting and a pipe end together radially.These press tools contain clamping components with clamping jaws, whichin the pressing process are moved radially to form a closed pressingspace. In addition to press tools having two clamping jaws (DE-A-34 23283; DE-A-38 33 748), press tools having more than two clamping jaws,which permits greater insertion depths, are also known-in-the-art. Thelatter type of press tools can be found, specifically, in EP-A-0 451806. In relation to this, the press tools illustrated in FIGS. 7 and 8are of particular interest, as they are suited for the joining of pipeends that are large and very large in diameter.

As may be found in the similar type DE-C2-38 33 748, the clamping jawsin such press tools contain on their inner side a specificcross-sectional shape that conforms to the shape of the press fitting.Because such press fittings have at their open end an annular ring thatprotrudes toward the outside, and on the inner side of which a conicalnipple is inserted, the clamping jaw contains a pressing groove that isshaped to receive this annular ring. The individual segments of thepressing groove in the clamping jaws join to form a continuouscircumferential pressing groove.

In order that the annular ring is not simply pressed onto the pipe end,effecting instead a pressing process between the press fitting and thepipe end, in addition to the annular ring, pressing lands extend on bothsides of the pressing groove, which become pressed during the pressingprocess into the material of the press fittings, and thereby also thenested pipe end. As may also be found in DE-C2-38 33 748, the inclusionof pressing lands on both sides of the pressing groove is not anabsolute requirement for the pressing process. However, handling isfoolproof when the cross-section of the clamping jaw is symmetrical,that is, when pressing lands extend on both sides of the pressinggroove, because it then becomes irrelevant in which position the presstool is applied to the point that is to be pressed.

In the application of a press tool of the type described in thebeginning, in which the cross-section of the clamping jaws issymmetrical, it has been shown that the pressing land that lies on theopen end of the press fitting, in the final phase of the pressingprocess, also comes to be applied to the pipe, where it causes aconstriction of the pipe. Aside from the fact that this increases theamount of pressing force that must be applied, the elastic tension ofthe conical nipple is reduced via the pressing of the annular ring, sothat the maintenance of the required tightness over a period of yearscan no longer be ensured. In the worst case, a fissure could even formin the area of the seal, which would result in leakage.

It is thus the object of the invention to design a press tool of thetype described at the beginning, that will allow the maintenance ofmounting safety while permitting pressing that will not affecttightness.

This object is attained in accordance with the invention in that atemplate which fits over the nested workpiece but not over the slid-onworkpiece is positioned toward the other side of the groove.

With a press tool of this type, foolproof handling is ensured, despitethe fact that a pressing land is positioned along only one side of thegroove. This permits the advantages of press tools having asymmetricalclamping jaws to be realized without adversely affecting mountingsafety. The main advantage is that deformations of the pipe in the areaof the open end of the press fitting are avoided, thus the elastictension in the conical nipple is not impeded as a result of pressure onthe annular ring. This increases mounting safety as well as theguarantee of tightness over a period of years.

It should be noted that a specific press tool is suitable only forpressing a workpiece having a specific diameter, thus any reference to aworkpiece also contains information regarding the dimensions of thepress tool. The additional attachment of a template prevents the presstool from being mounted in a wrong position, in which the pressing landwould end up on the side of the annular ring that is closest to the openend of the press fitting, because in this position, the templateprevents mounting on the pressing point at the wrong position, at whichthe pressing land would lie on the side of the annular ring that isdirected toward the open end of the press fitting; in this position thetemplate prevents any application of the press tool because it does notfit over the press fitting. Only in the reverse position, in which thetemplate lies outside of the press fitting, is it possible to apply thepress tool.

The template is comprised, in a particularly simple design, of acorrespondingly shaped, metal component which is affixed to one of theclamping components.

In the diagrams, the invention is illustrated in greater detail withreference to one exemplary embodiment.

These diagrams show:

FIG. 1--the wraparound ring of a press tool in an opened position;

FIG. 2--the wraparound ring in accordance with FIG. 1 in a closedposition;

FIG. 3--a sectional view of the coupling member of the wraparound ringin accordance with FIGS. 1 and 2 as indicated by plane A-B, with thecoupling member in a loose position;

FIG. 4--the coupling member in the representation in accordance withFIG. 3, in a taut position;

FIG. 5--the wraparound ring in accordance with FIGS. 1 through 4 in itsposition following the pressing process; and

FIG. 6--a longitudinal section of the wraparound ring with pipe end andpress fitting, after it has been mounted onto the workpiece.

In FIGS. 1, 2, and 5, a cross-section of a pipe end (1) and a pressfitting (2) that has been slid onto the pipe end, with an annular ring(3) that contains a conical nipple, are indicated by a dot-dashed line.The pipe end (1) and press fitting (2) are to be pressed using a presstool (4), of which only the wraparound ring (5) is illustrated in FIGS.1, 2, and 5.

The wraparound ring (5) in this exemplary embodiment contains clampingcomponents (6, 7, 8, 9, 10) that are essentially identical in design,with each clamping component (6, 7, 8, 9, 10) being comprised of anouter clamping bracket (11, 12, 13, 14, 15) and an inner, curved,clamping jaw (16, 17, 18, 19, 20). With one exception, the clampingbrackets are connected to one another via adapters (21, 22, 23, 24),with the clamping brackets (11, 12, 13, 14, 15) being hinged via hingepins (26, 27, 28, 29, 30, 31, 32, 33) to the adapters (21, 22, 23, 24).

In each case at least one hinge pin (26, 27, 28, 29, 30, 31, 32, 33) peradapter (21, 22, 23, 24) is designed to be removable, so that thewraparound ring (5) can be dismantled into individual clampingcomponents (6, 7, 8, 9, 10) or can be assembled from these on the spot.The clamping jaws (16, 17, 18, 19, 20) are positioned in the clampingbrackets (11, 12, 13, 14, 15) such that they can shiftcircumferentially.

A clamping device (34, 35, 36, 37, 38) is attached to each clampingbracket (11, 12, 13, 14, 15) and contains a clamping piston (39, 40, 41,42, 43) that is directed radially toward the inside and is held underspring tension. The clamping devices (34, 35, 36, 37, 38) also serve inthe axial guidance of the clamping jaws (16, 17, 18, 19, 20).

The hinge pins (29, 30) on the center clamping bracket (13) support ajaw-shaped template (44) in the form of a metal component containing asemi-circular recess (45), in which the radius of the recess (45) issuch that the template (44) fits over the pipe end (1) but not over thecylindrical portion of the press fitting (2) that is adjacent to theannular ring (3). This ensures that the wraparound ring (5) can beplaced around the combination of pipe end (1) and press fitting (2) inonly one, preferred way.

The lower clamping components (6, 10) have between them, in thepositions indicated in FIGS. 1 and 2, a closing gap (46). In FIG. 1 thisgap is large enough that the wraparound ring (5) can be placed over thepress fitting (2) and the pipe end (1). The free ends of the clampingcomponents (6, 10) that are adjacent to the closing gap (46) containhinge pins (47, 48), with a coupling bracket (49, 50) being suspendedfrom each hinge pin (47, 48). The shape of the coupling brackets (49,50) and their connection to the hinge pins (47, 48) are indicatedspecifically in the sectional illustration in accordance with FIGS. 3and 4.

The free ends of the coupling brackets (49, 50) contain openings (51,52). A coupling pin (53) is inserted axially into the boring (51) in thecoupling bracket (49). This pin contains a first pin segment (54), whichextends through the boring (51). One end of the first pin segment (54)is connected to a hand lever (55). At the other end of the first pinsegment (54) is a second pin segment (56), the axis of which isdisplaced in relation to the first pin segment (54) by a degree ofeccentricity (57). The second pin segment (56) fits into the boring (52)in the other coupling bracket (50). The coupling brackets (49, 50),together with the coupling pins (53), form a coupling element for thetemporary connection of the ends of the wraparound ring (5) prior to theactual pressing process.

As is apparent from the illustration in FIG. 6, the clamping jaws (16,17, 18, 19, 20) are directed not only axially via the clamping devices(34, 35, 36, 37, 38), but also via guide plates (62) that are screwedonto the other side of the clamping brackets (11, 12, 13, 14, 15). Theclamping jaws (16, 17, 18, 19, 20) themselves are asymmetrical in theircross-section.

They contain a ring groove (63), with the pressing grooves (63) of allthe clamping jaws (16, 17, 18, 19, 20) combining to form a continuouscircumferential ring groove. The cross-section of the pressing groove(63) conforms to the annular ring (3), which has on its inner side aconical nipple (64).

A pressing land (65) extends along one side of the ring groove (63). Italso combines with the pressing lands of the other clamping jaws (16,17, 18, 19, 20) to form a continuous circumferential pressing land. Thepressing land (65) is intended to dig into the material of the pressfitting (2) during the pressing process, and also to dig into the pipeend (1) in order to shape it. No such pressing land is present on theother side of the ring groove (63).

In a pressing process, the opened wraparound ring (5) is first placedover the pipe end (1) and the press fitting (2), as is indicated inFIGS. 1 and 6. When the wraparound ring (5) is on the pipe end (1) orpress fitting (2), the two lower clamping components (6, 10) are swungtoward one another and on the pipe end (1), so that they assume theposition illustrated in FIG. 2. The coupling brackets (49, 50) that thenremain suspended, a position which is indicated in FIG. 2 by adot-dashed line, are then swung toward one another in the directions ofarrows C and D. The coupling pin (53) is then in a position in which itssecond pin segment (56) does not protrude from the boring (51), which isindicated in FIG. 3 by the dot-dashed line indicating the position ofthe hand lever (55).

The horizontal sweep of the coupling brackets (49, 50) continues up tothe position at which they overlap and the borings (51, 52) merge. Thecoupling pin (53), and thereby also the hand lever (55), are then in aposition in which the second pin segment (56) is shifted toward theother coupling bracket (50), and can thus easily be set into its boring(52) via the axial shifting of the coupling pin (53), and can therebyjoin the two coupling brackets (49, 50). In this position, thewraparound ring (5) still maintains a certain degree of slack.

The hand lever (55) is then swung 180° from the position indicated inFIG. 2 by solid lines, into the position indicated by a dot-dashed line,in the direction of the arrow E. This causes the second pin segment (56)to execute an eccentric motion and to shorten the distance between thetwo hinge pins (47, 48) by double the eccentricity (57). This is madeclear in the comparison of FIGS. 3 and 4, with FIG. 4 illustrating theswung position. This movement exerts a peripheral force on thewraparound ring (5), which causes the clamping jaws (16, 17, 18, 19, 20)to press with a certain degree of radial tension on the press fitting(2). The wraparound ring (5) then has a fit that cannot be rotated or isat least very difficult to rotate. This effect is enhanced by theclamping pistons (39, 40, 41, 42, 43), which then press against the pipeend (1) with equal, radially directed tension.

Now the actual pressing process can begin. In this process, a closingdevice, which will not be described in greater detail and is part of thepress tool (4), is used, as is known schematically from FIG. 7 of EP-A-0451 806. This closing device contains two tong-shaped lever arms, bymeans of which the closing device can be attached to the hinge pins (47,48). This causes them to extend through spaces (58, 59) or (60, 61) andto be adjacent to the outsides of the hinge pins (47, 48). Thetong-shaped lever arms are then brought together by means of a hydraulicmotor that is part of the closing device, so that the hinge pins (47,48) approach one another. The result of this is that the wraparound ring(5) becomes constricted, which causes the press fitting (2) and the pipeend (1) to be radially compressed, in which the pressing land (64) digssomewhat into the material of the press fittings (2) and the annularring (3) is pressed against the pipe end (1), such that the conicalnipple (64) becomes pressed onto the pipe end (1) with an amount ofradial pressure that is necessary to ensure a good seal. In thisprocess, the clamping jaws (16, 17, 18, 19, 20) are automaticallydisplaced circumferentially, to the point at which the surfaces of theclamping jaws (16, 17, 18, 19, 20) are touching. At the same time, thecoupling brackets (49, 50) yield toward the outside, which keeps themfrom interfering with the pressing process. Following the conclusion ofthe pressing process, the wraparound ring (5) assumes the positionillustrated in FIG. 5. After the axial displacement of the coupling pin(53), which causes the second pin segment (56) to slip out of the boring(52), the wraparound ring (5) can be removed and used for other pressingprocesses.

I claim:
 1. Press tool for pressing tubular, inner and outer nestedworkpieces (1, 2), in particular a pipe end (1) upon which is slid apress fitting (2), said press tool comprising several clampingcomponents (6, 7, 8, 9, 10) that contain clamping jaws (16, 17, 18, 19,20) with a continuous circumferential pressing groove (63) shaped intheir inner sides, said jaws having a pressing land (65) that protrudesand extends along only one side of the pressing groove (63), there beingno such pressing land (65) on the other side of said pressing groove(63), and a template (44) which fits over the inner nested workpiece (1)but not over the outer and slid-on workpiece (2), said template beingpositioned on the other side of the pressing groove from the pressingland, and wherein there is no such template (44) on the pressing landside of said pressing groove.
 2. Press tool in accordance with claim 1,characterized in that the template (44) is shaped so as to have asemi-circular recess.
 3. Press tool in accordance with claim 2,characterized in that the template is comprised of a metal componentthat is affixed to one of the clamping components (8).
 4. Press tool inaccordance with claim 1, characterized in that the template is comprisedof a metal component that is affixed to one of the clamping components(8).
 5. A press tool used in radially pressing together a tubular pipeend (1) and a tubular press fitting (2) slid thereonto, the press toolcomprising:a plurality of radially clamping components includingclamping jaws for circumferentially surrounding the tubular pipe end andpress fitting to be radially pressed; a continuous pressing groove (63)defined in inner sides of said clamping components, said groove tocircumferentially surround said pipe end and press fitting; a pressingland (65) protruding inwardly from a surface of said clamping componentsand extending along only one side of said pressing groove on the innerside of said clamping components, there being no such pressing land (65)on the other side of said pressing groove, said pressing land forcircumferentially surrounding said pipe end and said press fitting; anda template (44) which fits over the pipe end (1), but not over the pressfitting (2), said template being located on the other side of saidpressing groove from said pressing land so that the clamping componentscan be placed around the tubular pipe end and tubular press fitting inonly one way, and wherein there is no such template on the pressing landside of said pressing groove.
 6. The press tool of claim 5, wherein eachclamping component includes an outer clamping bracket and one of saidclamping jaws.
 7. The press tool of claim 6, wherein a plurality of saidclamping brackets include clamping pistons directed radially inward andheld under tension.
 8. The tool of claim 5, further comprising a handlever (55) which when swung causes a pin segment (56) to execute aneccentric motion to shorten the distance between two hinge pins (47,48).